Known roofing systems for sloping roofs, such as shingles made of asphalt, terracotta and the like, do not provide ventilation underneath the shingles and it frequently happens in cold climates that humidity from the house condenses underneath the shingles, and there is produced ice formation at the edge of the roof, which blocks water run-off and causes water infiltration. Heating wires to melt the ice must therefore be installed over the shingles. This is unsightly and difficult of upkeep.
The joints between known shingles forming a roof covering are not waterproof, especially under the action of windswept rain and, therefore, there is often water infiltration under high wind condition.
Known heat insulating shingles possess the same disadvantages.
Terracotta tiles, which impart good aesthetics to a roof, are fragile and, therefore, are difficult to handle; are heavy and thus require roof reinforcement and also suffer from ice formation and water infiltration by wind-swept rain.